cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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context.h (2426B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2#ifndef __X86_KERNEL_FPU_CONTEXT_H
      3#define __X86_KERNEL_FPU_CONTEXT_H
      4
      5#include <asm/fpu/xstate.h>
      6#include <asm/trace/fpu.h>
      7
      8/* Functions related to FPU context tracking */
      9
     10/*
     11 * The in-register FPU state for an FPU context on a CPU is assumed to be
     12 * valid if the fpu->last_cpu matches the CPU, and the fpu_fpregs_owner_ctx
     13 * matches the FPU.
     14 *
     15 * If the FPU register state is valid, the kernel can skip restoring the
     16 * FPU state from memory.
     17 *
     18 * Any code that clobbers the FPU registers or updates the in-memory
     19 * FPU state for a task MUST let the rest of the kernel know that the
     20 * FPU registers are no longer valid for this task.
     21 *
     22 * Either one of these invalidation functions is enough. Invalidate
     23 * a resource you control: CPU if using the CPU for something else
     24 * (with preemption disabled), FPU for the current task, or a task that
     25 * is prevented from running by the current task.
     26 */
     27static inline void __cpu_invalidate_fpregs_state(void)
     28{
     29	__this_cpu_write(fpu_fpregs_owner_ctx, NULL);
     30}
     31
     32static inline void __fpu_invalidate_fpregs_state(struct fpu *fpu)
     33{
     34	fpu->last_cpu = -1;
     35}
     36
     37static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu)
     38{
     39	return fpu == this_cpu_read(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
     40}
     41
     42static inline void fpregs_deactivate(struct fpu *fpu)
     43{
     44	__this_cpu_write(fpu_fpregs_owner_ctx, NULL);
     45	trace_x86_fpu_regs_deactivated(fpu);
     46}
     47
     48static inline void fpregs_activate(struct fpu *fpu)
     49{
     50	__this_cpu_write(fpu_fpregs_owner_ctx, fpu);
     51	trace_x86_fpu_regs_activated(fpu);
     52}
     53
     54/* Internal helper for switch_fpu_return() and signal frame setup */
     55static inline void fpregs_restore_userregs(void)
     56{
     57	struct fpu *fpu = &current->thread.fpu;
     58	int cpu = smp_processor_id();
     59
     60	if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
     61		return;
     62
     63	if (!fpregs_state_valid(fpu, cpu)) {
     64		/*
     65		 * This restores _all_ xstate which has not been
     66		 * established yet.
     67		 *
     68		 * If PKRU is enabled, then the PKRU value is already
     69		 * correct because it was either set in switch_to() or in
     70		 * flush_thread(). So it is excluded because it might be
     71		 * not up to date in current->thread.fpu.xsave state.
     72		 *
     73		 * XFD state is handled in restore_fpregs_from_fpstate().
     74		 */
     75		restore_fpregs_from_fpstate(fpu->fpstate, XFEATURE_MASK_FPSTATE);
     76
     77		fpregs_activate(fpu);
     78		fpu->last_cpu = cpu;
     79	}
     80	clear_thread_flag(TIF_NEED_FPU_LOAD);
     81}
     82
     83#endif